Re: [PATCH 1/1 v2] kbd: Limit the kbdrate application to x86, mips and sparc

[jhuang0 <jackie.huang@windriver.com>]

On 7/12/2013 4:34 PM, Phil Blundell wrote:
> On Fri, 2013-07-12 at 13:42 +0800, jackie.huang@windriver.com wrote:
>> The code relies on hardware specific memory locations to access
>> and modify the keyboard repeat rate.  It also requires read/write
>> access to /dev/port which doesn't exist on every architecture's
>> root fs. The defect was raised for Qemu PowerPC but it also fails on
>> ARM.  The keyboard emulation in qemuppc is for an ADB (Apple Desktop
>> Bus) device and not compatible with an Intel driver.  There's also no
>> indication in the documentation that the code should work on anything
>> other than Intel architecture but it also works on MIPS.
>
> This reasoning seems slightly spurious.  There do exist ARM and PPC
> machines where kbdrate works, it's just that the hardware emulated by
> qemuarm and qemuppc doesn't happen to fall into that category.  Equally,
> there are certainly mips machines (and might conceivably be some
> x86/sparc ones) where it doesn't work.  So I don't think you can make
> any sensible determination about the supportedness or not of kbdrate
> based on TARGET_ARCH alone.
>
> Of course, the right answer really is for rate setting to go through the
> kernel driver (which knows what sort of hardware it is using) rather
> than for kbdrate to go poking at random I/O ports.

Thanks Phil, I will re-work and do more anaysis on it.

Thanks,
Jackie

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-- 
Jackie Huang
WIND RIVER | China Development Center
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